Woody's Workshop – Page 26 – Keeping the Grey Matter active

December 5, 2021

Haimer Taster and vacuum table retrospective thoughts

Today while in the workshop running a CNC metalwork job and then following this with running a quick PCB artwork, the following came to mind.

These days since I bought the ITTP Hallmark probe I rarely use my Haimer Taster to do my referencing. It still has its uses but less and less so. A good example is when remounting the CNC vice on the tooling table. I use the Haimer to give me a running check on the vice jaw axis tracking. Beyond that the ITTP in conjunction with PathPilot probing routines meet all my referencing needs to a level of accuracy that suits.

The other thing that stuck me is how automated my process for milling printed circuit board prototypes has become. Fusion 360 Electrical module becomes more familiar to me with each passing project. It exports my PCB designs as Gerber files to import into FlatCAM. After a few clicks in FlatCAM I have a GCode file for drilling and routing. The PCB blank is gripped on my small vacuum table ready for milling and the ITTP probe references the spindle. My recent use of kitchen anti-slip material as the sacrificial layer between PCB and vacuum table top surface has made the grip on the vacuum table so much easier to achieve. The overall PCB process, whether single or double sided, has become quick, easy and repeatable. Once the board is milled I can get a reasonable looking tinned finish using a hand soldering iron and copious amounts of flux.

Techniques almost subconsciously evolve and sometimes you need to step back and see how far you have come along the road. The alternative view might be that this ‘lazy man’ has just become even more lazy.

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December 1, 2021December 5, 2021

Shopping list spreadsheet that has other uses

This one is way off beam …. an enquiry for help appeared on the Model Engineering Workshop forum for a simple shopping list when buying groceries etc.

Excel has a facility to create a special version of a spreadsheet called a pivot table. In short this is a table that contains columns and lines but each column has a header that is automated to allow sorting of the table by that particular column. Not only does the column sort the full table but you can refine the data to just show and sort lines of interest. It is easy to use, no macro skills needed just click and sort. I love pivot tables …. well lets be honest I love Excel. So many possible uses for lines and columns.

The spreadsheet is on my download page and is stored as a ZIP file.

The table allows you to have multiple entries for the same produce from different stores and for each store there is a location in the store and a price for the item in that store. So you can have different sorts of bread from different stores and all at different prices. To go shopping you put a ‘Y’ in the Buy column. Here is a screenshot (with random pricing I entered to try it out).

Once you have the ‘Y’ on the items of interest you get a price for the total shop. You can then click on the Buy column header down arrow and a dialogue box comes up that asks how you want to sort. By selecting just the Y entries you get a unique list for today’s shop. Once you have the Ys only, you can then sub sort by store and by aisle or location in the store. Once you have something that suits your expedition, print the active area by highlighting and using Print Selection and off you go with a prompt of what you should be looking for as you walk round each store.

There are no macros, no complex formula and anyone can use it.

OK it is a bit over the top for shopping but as the years pass we tend to forget what we went to the shops for in the first place. We also tend not to see the price creep from week to week. Maybe it will help someone ?

More importantly the pivot table could be modified to become a workshop asset register. Change the headings to Item, Manufacturer, Source, Location, Price Paid (the price you paid or the price you told your wife you paid ?) etc and you begin to look organised. The grim reaper arrives and your family now have a listing of what you had hidden away, where precisely and at what value. They are now a step ahead and they are less likely to get ripped off by the workshop clearance bandits. Think about it, it could be time well spent.

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November 22, 2021

Plastic heat sealer – a useful workshop asset

Clough42 has just posted making a protective cover for his plasma cutter control screen. As ever with James it is engineering perfection with stitched corners.

My lazy way (as ever) is to make such items using polythene plastic sheeting and a heat sealer.

This allows me to quickly make bespoke covers and pockets for all manner of applications. Here are a few examples.

All my silver steel is stored in such pockets and has the size written on the sleeve using a Sharpie.

The rear DRO scale on my VMB has an open ended pocket either side of the vice that acts as a concertina cover to keep cutting oil from affecting the scale reader.

So another useful tool to have available (without having to thread a needle).

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November 22, 2021September 29, 2022

Dewpoint alarm monitor to help avoid rust issues in the workshop

A Dewpoint Monitor to protect the workshop

I have recently read a number of posts on workshop forums about rust degrading workshop assets. When the temperature of the air reaches close to the dew point then the moisture in the air will condense on the cold surfaces in the workshop and moisture will inevitably lead to rust forming.

You can protect against this to some extent by ensuring that all exposed surfaces are coated with lubricant of some sort such as WD40 and only dry sources of heat are used in the workshop. A better protection solution which was popularised by the clockmaker William Smith, is make a 50/50 mix of linseed oil and thinners and coat this on the objects needing protection. This works well but does not last forever.

Looking around on the internet there are various Arduino projects to create a dewpoint monitor using the DTH11/DTH22 which are combined temperature and moisture probes. Such devices, with a little bit of maths, can provide an alarm output if the dewpoint reaches close to the air temperature. This could be used to turn on a heater and raise the air temperature and avoid moisture being deposited. I opted to have the sensor remote via a cabled connection.

The dew point calculation I used is the Magnus-Tetens formula (Sonntag90). This provides accurate results (with an uncertainty of 0.35°C) for temperatures ranging from -45°C to 60°C.

The dew point is calculated according to the following formula:

Ts = (bα(T,RH)) / (a – α(T,RH))

where:

Ts is the dew point;
T is the temperature;
RH is the relative humidity of the air;
a and b are coefficients.

The Sonntag90 constant values are : – –

a = 17.62 and b = 243.12°C;

and this is the final formula needed : –

α(T,RH) = ln(RH/100) + aT/(b+T).

I made a prototype using an Arduino Pro Mini as the controller and I used the above equation to calculate the dewpoint from the humidity and temperature readings input to the Arduino from the DTH22 sensor. Once the dewpoint reaches within a defined limit of the temperature, a relay is closed to allow heaters to be turned on. This trip point also causes the LCD display flash to warn that a trip point has been reached.

The working circuit was drawn in Fusion Electrical and a printed circuit board layout was created. Fusion’s Electrical CAM output as Gerber and Epsilon files were converted in FlatCAM to CNC GCode. The CNC files were than posted to my Tormach PCNC440 to mill the copper traces.

I designed the PCB using through hole components to make assembly easier for my more mature eyesight.

The trigger output from the PCB can feed any 5V coil relay that is rated with contacts capable of feeding the AC voltage and current needed for the heaters.

UPDATE 18/12/2021

Due to demand I have ordered a small quantity of offshore manufactured PCBs for the Dewpoint Monitor. If you are interested in one then send me an email as per address below. First come first serve.

UPDATE 1/11/2022

Auto reset code added should the sensor lose connectivity,

New write up is below including the new code

Humidity-Monitor-v2 Download

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November 17, 2021November 17, 2021

Engineering Video Favourites Updated List

As the months (and years !) have passed while authoring this site, my favourite YouTube sites have morphed and changed as my skill level and interests have become more focussed. The other aspect is that many of my early favourites have just faded away and now rarely post if at all. I guess it takes a great deal of commitment to create regular footage over a long period of time so it is understandable that people come and go.

At the risk of everyone clicking and leaving, here is a share of the sites I now look forward to visiting and viewing : –

Top of the list is Clough42 for his highly professional, regular posts on home workshop activity but key for me is his use of Fusion 360 for all his engineering modelling.

I met Jimmy Diresta at NYC CNC in 2016 and I love to watch his almost ‘off the cuff’ creations in metal and wood.

For TIG welding I have watched many sources but Pacific Arc TIG Welding is my current favourite and Dusty does some amazing stainless TIG welding artworks.

I need to mention This Old Tony even though he has been absent from the scene for a long period. He is now back and on top form.

Then of course for serious CNC activity there is John Saunders and John Grimsmo. Both these guys have done incredibly well as they have emerged from their garages and blossomed into YouTube stars.

Finally a less well know site for Fusion 360 is Mechanical Advantage hosted by Kevin who was my instructor on the NYC CNC Fusion 360 course. Really nice guy and always helpful if you have a problem.

So that is my current short list of ‘ones to watch’. If you haven’t discovered any of them then check them out. But don’t forget to come back here every now and then just in case I get up to something interesting.

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